RFC 2742 Agent X MIB January 20001. The SNMP Management Framework
The SNMP Management Framework presently consists of five major
components:
- An overall architecture, described in RFC 2571 [1].
- Mechanisms for describing and naming objects and events for the
purpose of management. The first version of this Structure of
Management Information (SMI) is called SMIv1 and described in STD
16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The
second version, called SMIv2, is described in STD 58, RFC 2578
[5], STD 58, RFC 2579 [6] and STD 58, RFC 2580 [7].
- Message protocols for transferring management information. The
first version of the SNMP message protocol is called SNMPv1 and
described in STD 15, RFC 1157 [8]. A second version of the SNMP
message protocol, which is not an Internet standards track
protocol, is called SNMPv2c and described in RFC 1901 [9] and RFC1906 [10]. The third version of the message protocol is called
SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and RFC 2574
[12].
- Protocol operations for accessing management information. The
first set of protocol operations and associated PDU formats is
described in STD 15, RFC 1157 [8]. A second set of protocol
operations and associated PDU formats is described in RFC 1905
[13].
- A set of fundamental applications described in RFC 2573 [14] and
the view-based access control mechanism described in RFC 2575
[15].
A more detailed introduction to the current SNMP Management Framework
can be found in RFC 2570 [16].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the mechanisms defined in the SMI.
This memo specifies a MIB module that is compliant to the SMIv2. A
MIB conforming to the SMIv1 can be produced through the appropriate
translations. The resulting translated MIB must be semantically
equivalent, except where objects or events are omitted because no
translation is possible (use of Counter64). Some machine readable
information in SMIv2 will be converted into textual descriptions in
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RFC 2742 Agent X MIB January 2000
SMIv1 during the translation process. However, this loss of machine
readable information is not considered to change the semantics of the
MIB.
2. Introduction
The SNMP Agent Extensibility Protocol (AgentX) is a protocol used to
distribute the implementation of an SNMP agent amongst a single
"master agent" and multiple "subagents". See [17] for details about
the AgentX protocol.
The goals of the AgentX MIB are:
- List the set of subagent connections that currently have logical
sessions open with the master agent.
- Identify each subagent connection transport address and type.
- Identify each subagent session vendor, AgentX protocol version,
and other characteristics.
- Identify the set of MIB objects each session implements, the
context in which the objects are registered, and the priority of
the registration.
- Determine protocol operational parameters such as the timeout
interval for responses from a session and the priority at which a
session registers a particular MIB region.
- Allow (but do not require) managers to explicitly close subagent
sessions with the master agent.
3. AgentX MIB Overview
This MIB is organized into four groups. The agentxGeneral group
provides information describing the master agent's AgentX support,
including the protocol version supported. The agentxConnection group
provides information describing the current set of connections
capable of carrying AgentX sessions. The agentxSession group
provides information describing the current set of AgentX sessions.
The agentxRegistration group provides information describing the
current set of registrations.
Three tables form the heart of this mib. These are the connection,
session, and registration tables.
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RFC 2742 Agent X MIB January 2000
used to support zero or more AgentX sessions. An entry is
created when a new transport connection is established,
and is destroyed when the transport connection is terminated.
"
INDEX { agentxConnIndex }
::= { agentxConnectionTable 1 }
AgentxConnectionEntry ::= SEQUENCE {
agentxConnIndex Unsigned32,
agentxConnOpenTime TimeStamp,
agentxConnTransportDomain TDomain,
agentxConnTransportAddress AgentxTAddress }
agentxConnIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"agentxConnIndex contains the value that uniquely identifies
an open transport connection used by this master agent
to provide AgentX service. Values of this index should
not be re-used. The value assigned to a given transport
connection is constant for the lifetime of that connection.
"
::= { agentxConnectionEntry 1 }
agentxConnOpenTime OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime when this connection was established
and, therefore, its value when this entry was added to the table.
"
::= { agentxConnectionEntry 2 }
agentxConnTransportDomain OBJECT-TYPE
SYNTAX TDomain
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The transport protocol in use for this connection to the
subagent.
"
::= { agentxConnectionEntry 3 }
agentxConnTransportAddress OBJECT-TYPE
SYNTAX AgentxTAddress
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RFC 2742 Agent X MIB January 2000
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The transport address of the remote (subagent) end of this
connection to the master agent. This object may be zero-length
for unix-domain sockets (and possibly other types of transport
addresses) since the subagent need not bind a filename to its
local socket.
"
::= { agentxConnectionEntry 4 }
-- The AgentX Subagent Session Group
agentxSessionTableLastChange OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime when the last row creation or deletion
occurred in the agentxSessionTable.
"
::= { agentxSession 1 }
agentxSessionTable OBJECT-TYPE
SYNTAX SEQUENCE OF AgentxSessionEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A table of AgentX subagent sessions currently in effect.
"
::= { agentxSession 2 }
agentxSessionEntry OBJECT-TYPE
SYNTAX AgentxSessionEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information about a single open session between the AgentX
master agent and a subagent is contained in this entry. An
entry is created when a new session is successfully established
and is destroyed either when the subagent transport connection
has terminated or when the subagent session is closed.
"
INDEX { agentxConnIndex, agentxSessionIndex }
::= { agentxSessionTable 1 }
AgentxSessionEntry ::= SEQUENCE {
agentxSessionIndex Unsigned32,
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RFC 2742 Agent X MIB January 2000
agentxSessionObjectID OBJECT IDENTIFIER,
agentxSessionDescr SnmpAdminString,
agentxSessionAdminStatus INTEGER,
agentxSessionOpenTime TimeStamp,
agentxSessionAgentXVer INTEGER,
agentxSessionTimeout INTEGER
}
agentxSessionIndex OBJECT-TYPE
SYNTAX Unsigned32 (0..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A unique index for the subagent session. It is the same as
h.sessionID defined in the agentx header. Note that if
a subagent's session with the master agent is closed for
any reason its index should not be re-used.
A value of zero(0) is specifically allowed in order
to be compatible with the definition of h.sessionId.
"
::= { agentxSessionEntry 1 }
agentxSessionObjectID OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"This is taken from the o.id field of the agentx-Open-PDU.
This attribute will report a value of '0.0' for subagents
not supporting the notion of an AgentX session object
identifier.
"
::= { agentxSessionEntry 2 }
agentxSessionDescr OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A textual description of the session. This is analogous to
sysDescr defined in the SNMPv2-MIB in RFC 1907 [19] and is
taken from the o.descr field of the agentx-Open-PDU.
This attribute will report a zero-length string value for
subagents not supporting the notion of a session description.
"
::= { agentxSessionEntry 3 }
agentxSessionAdminStatus OBJECT-TYPE
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RFC 2742 Agent X MIB January 2000
SYNTAX INTEGER {
up(1),
down(2)
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The administrative (desired) status of the session. Setting
the value to 'down(2)' closes the subagent session (with c.reason
set to 'reasonByManager').
"
::= { agentxSessionEntry 4 }
agentxSessionOpenTime OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime when this session was opened and,
therefore, its value when this entry was added to the table.
"
::= { agentxSessionEntry 5 }
agentxSessionAgentXVer OBJECT-TYPE
SYNTAX INTEGER (1..255)
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The version of the AgentX protocol supported by the
session. This must be less than or equal to the value of
agentxMasterAgentXVer.
"
::= { agentxSessionEntry 6 }
agentxSessionTimeout OBJECT-TYPE
SYNTAX INTEGER (0..255)
UNITS "seconds"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The length of time, in seconds, that a master agent should
allow to elapse after dispatching a message to this session
before it regards the subagent as not responding. This value
is taken from the o.timeout field of the agentx-Open-PDU.
This is a session-specific value that may be overridden by
values associated with the specific registered MIB regions
(see agentxRegTimeout). A value of zero(0) indicates that
the master agent's default timeout value should be used
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RFC 2742 Agent X MIB January 2000
agentxRegIndex OBJECT-TYPE
SYNTAX Unsigned32 (1..4294967295)
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"agentxRegIndex uniquely identifies a registration entry.
This value is constant for the lifetime of an entry.
"
::= { agentxRegistrationEntry 1 }
agentxRegContext OBJECT-TYPE
SYNTAX OCTET STRING
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The context in which the session supports the objects in this
region. A zero-length context indicates the default context.
"
::= { agentxRegistrationEntry 2 }
agentxRegStart OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The starting OBJECT IDENTIFIER of this registration entry. The
session identified by agentxSessionIndex implements objects
starting at this value (inclusive). Note that this value could
identify an object type, an object instance, or a partial object
instance.
"
::= { agentxRegistrationEntry 3 }
agentxRegRangeSubId OBJECT-TYPE
SYNTAX Unsigned32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"agentxRegRangeSubId is used to specify the range. This is
taken from r.region_subid in the registration PDU. If the value
of this object is zero, no range is specified. If it is non-zero,
it identifies the `nth' sub-identifier in r.region for which
this entry's agentxRegUpperBound value is substituted in the
OID for purposes of defining the region's upper bound.
"
::= { agentxRegistrationEntry 4 }
agentxRegUpperBound OBJECT-TYPE
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RFC 2742 Agent X MIB January 2000
SYNTAX Unsigned32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"agentxRegUpperBound represents the upper-bound sub-identifier in
a registration. This is taken from the r.upper_bound in the
registration PDU. If agentxRegRangeSubid (r.region_subid) is
zero, this value is also zero and is not used to define an upper
bound for this registration.
"
::= { agentxRegistrationEntry 5 }
agentxRegPriority OBJECT-TYPE
SYNTAX Unsigned32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The registration priority. Lower values have higher priority.
This value is taken from r.priority in the register PDU.
Sessions should use the value of 127 for r.priority if a
default value is desired.
"
::= { agentxRegistrationEntry 6 }
agentxRegTimeout OBJECT-TYPE
SYNTAX INTEGER (0..255)
UNITS "seconds"
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The timeout value, in seconds, for responses to
requests associated with this registered MIB region.
A value of zero(0) indicates the default value (indicated
by by agentxSessionTimeout or agentxDefaultTimeout) is to
be used. This value is taken from the r.timeout field of
the agentx-Register-PDU.
"
::= { agentxRegistrationEntry 7 }
agentxRegInstance OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of agentxRegInstance is `true' for
registrations for which the INSTANCE_REGISTRATION
was set, and is `false' for all other registrations.
"
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RFC 2742 Agent X MIB January 2000
agentxRegTimeout,
agentxRegInstance
}
STATUS current
DESCRIPTION
"All accessible objects in the AgentX MIB.
"
::= { agentxMIBGroups 1 }
END
5. Intellectual Property
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intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
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licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Heintz, et al. Standards Track [Page 15]

RFC 2742 Agent X MIB January 20006. Acknowledgements
This document is the result of the efforts of the IETF AgentX Working
Group (WG).
This MIB is an evolution of the Subagent MIB by Bert Wijnen
(wijnen@vnet.ibm.com) which in turn was derived from the SMUX-MIB by
Marshall Rose [18].
Thanks are in order to the following AgentX WG members:
Mike Daniele (Compaq Computer Corporation)
Dale Francisco (Cisco Systems)
Bob Natale (ACE*COMM Corporation)
Randy Presuhn (BMC Software, Inc.)
Shawn Routhier (Epilogue)
Mike Thatcher (Independent Consultant)
Special acknowledgement is made to:
Maria Greene (Xedia)
Special acknowledgement is also made to the following individuals for
participating in the 1998 AgentX testing summit (bakeoff) held in
Sunnyvale, California:
Jeff Case (SNMP Research, Inc.)
Mike Daniele (Compaq Computer Corporation)
Mark Ellison (Ellison Software Consulting, Inc.)
Lauren Heintz (BMC Software, Inc.)
Verne Hyde (Independent Consultant)
Bob Natale (ACE*COMM Corporation)
Shawn Routhier (Epilogue)
Mike Thatcher (Independent Consultant)
Bert Wijnen (IBM T. J. Watson Research Center)
7. Security Considerations
There is a single management object defined in this MIB that has a
MAX-ACCESS clause of read-write. This object may be considered
sensitive or vulnerable in some network environments. The support
for SET operations in a non-secure environment without proper
protection can have a negative effect on network operations.
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RFC 2742 Agent X MIB January 2000
There is a single managed object in this MIB that may contain
sensitive information. This object is agentxSessionAdminStatus.
Setting agentxSessionAdminStatus to an inappropriate value can
effectively prevent access to management information, or provide
access to inappropriate information.
It is thus important to control even GET access to these objects and
possibly to even encrypt the values of these objects when sending
them over the network via SNMP. Not all versions of SNMP provide
features for such a secure environment.
SNMPv1 by itself is not a secure environment. Even if the network
itself is secure (for example by using IPSec), even then, there is no
control as to who on the secure network is allowed to access and
GET/SET (read/change/create/delete) the objects in this MIB.
It is recommended that the implementers consider the security
features as provided by the SNMPv3 framework. Specifically, the use
of the User-based Security Model RFC 2574 [12] and the View-based
Access Control Model RFC 2575 [15] is recommended.
It is then a customer/user responsibility to ensure that the SNMP
entity giving access to an instance of this MIB, is properly
configured to give access to the objects only to those principals
(users) that have legitimate rights to indeed GET or SET
(change/delete) them.
8. References
[1] Harrington, D., Presuhn, R. and B. Wijnen, "An Architecture for
Describing SNMP Management Frameworks", RFC 2571, April 1999.
[2] Rose, M. and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based Internets", STD 16, RFC1155, May 1990.
[3] Rose, M. and K. McCloghrie, "Concise MIB Definitions", STD 16,
RFC 1212, March 1991.
[4] Rose, M., "A Convention for Defining Traps for use with the
SNMP", RFC 1215, March 1991.
[5] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
M. and S. Waldbusser, "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
Heintz, et al. Standards Track [Page 17]

RFC 2742 Agent X MIB January 200010. Full Copyright Statement
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Heintz, et al. Standards Track [Page 20]